NFC: Require override keyword

CMakeLists.txt

@@ -419,6 +419,7 @@ else() # MSVC
   add_compile_flag("-Wswitch") # we explicitly expect this in the code
   add_compile_flag("-Wimplicit-fallthrough")
   add_compile_flag("-Wnon-virtual-dtor")
+  add_compile_flag("-Wsuggest-override")
 
   if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
     # Google style requires this, so make sure we compile cleanly with it.

src/passes/Outlining.cpp

@@ -662,7 +662,7 @@ struct ReconstructStringifyWalker
 };
 
 struct Outlining : public Pass {
-  void run(Module* module) {
+  void run(Module* module) override {
     HashStringifyWalker stringify;
     // Walk the module and create a "string representation" of the program.
     stringify.walkModule(module);

src/passes/Poppify.cpp

@@ -456,7 +456,7 @@ class PoppifyFunctionsPass : public Pass {
 } // anonymous namespace
 
 class PoppifyPass : public Pass {
-  void run(Module* module) {
+  void run(Module* module) override {
     PassRunner subRunner(getPassRunner());
     subRunner.add(std::make_unique<PoppifyFunctionsPass>());
     // TODO: Enable this once it handles Poppy blocks correctly